Jessica Peris has lashed out at anti-doping officials as the track sprinter vowed to fight any allegation she used a banned substance.
The daughter of Olympic gold medallist Nova Peris believes there are "substantial flaws" in the way the Australian Sports Anti-Doping Authority (ASADA) handled her urine samples.
Peris says she was notified last month that an A sample taken on October 18 had tested positive to a banned substance.
But she claims a blood sample taken the same day tested negative.
"A further test on a urine sample taken from me by ASADA only 34 hours later also tested negative," she said in a statement.
"I now believe that there are substantial flaws in the way in which my urine tests were conducted in respect of my urine sample to ASADA on 18 October."
ASADA has been contacted for comment.
Peris, 27, was in contention for Commonwealth Games selection after setting personal bests this summer over 100m and 200m, but the positive test meant she could not compete at the February 15-18 trials on the Gold Coast.
Sydney solicitor George Newhouse and Melbourne-based global sports law expert Paul Hayes SC are representing the sprinter.
"I am looking forward to fighting any doping allegation brought against me by ASADA and ensuring my reputation as a clean athlete continues," she said.
Peris's mother Nova was the first Indigenous Australian athlete to win Olympic gold, as a member of the Hockeyroos at the 1996 Atlanta Games.
She then switched to track sprinting, winning the 200m gold medal at the 1998 Commonwealth Games in Kuala Lumpur and competing at the 2000 Sydney Olympics.